1. Field of the Invention
The present invention relates generally to the separation and removal of fluids, such as drilling mud, additives and/or contaminants, from solid components of drill cuttings created during the oil and gas well drilling process. More particularly still, the present invention relates to a method and apparatus for the removal of entrained and/or adherent fluids from drill cuttings, thereby permitting recovery of such fluids, as well as efficient disposal of dried solid components of said drill cuttings.
2. Description of the Related Art
As an oil or gas well is being drilled, drilling fluids (often referred to as “drilling mud”) are typically pumped down the drill pipe, and circulated up the annular space existing between the drill pipe and the inner face of the wellbore. Drilling fluids circulated to the drilling rig and out of a well often contain pieces of broken rock and other solid debris from the well commonly referred to as “cuttings” or “drill cuttings”. In most cases, the drilling fluids leaving a well, together with associated drill cuttings, are directed to at least one device which is specifically designed to separate the drill cuttings from the mud. Such devices include, but are not limited to, “shale shakers,” desanders, desilters, hydrocyclones and centrifuges.
If drill cuttings are not removed from the effluent mud stream exiting a well, such cuttings would remain in the active mud system and would be recirculated into the well. However, such materials can dramatically alter the characteristics and performance of drilling mud in the well and, in turn, negatively impact the overall drilling process. Further, recirculation of drill cuttings can also increase wear and tear in mud pumps and other mechanical equipment utilized in the drilling process. As such, shale shakers and other similar devices are frequently necessary to efficiently separate the drill cuttings from the drilling mud as such mud is circulated out of a well.
In many cases, shale shakers utilize a series of screens arranged in tiered or flat disposition relative to one another. Such screens are often made to vibrate in order to encourage separation of liquids from the drill cuttings. The drilling fluids generally fall through the screens by gravity, while the solid cuttings typically pass over the end of the screens.
After drilled solids and other debris have been separated from the drilling mud effluent stream exiting a well, it is necessary to dispose of such cuttings. Unfortunately, the disposal of such drill cuttings can present a number of practical problems. In many cases, such drill cuttings are discharged directly into the surrounding environment. However, even though drill cuttings leaving a shale shaker or other separation device may have been separated from a well's effluent mud stream, such cuttings nonetheless typically include entrained and/or adherent mud and other fluids which could be damaging to the surrounding environment.
In order for drilling fluid to accomplish its intended objectives, it is often necessary to adjust or control certain characteristics of such drilling fluid. Frequently, chemicals and/or other additives are often incorporated into such drilling fluids. Many of these additives, as well as drilling fluids that are oil-based or synthetic-based, can be environmentally harmful. As such, it is often undesirable, and a violation of environmental laws or regulations, to release such fluid-laden cuttings directly into the surrounding environment.
In order to avoid environmental contamination and comply with applicable governmental regulations, drill cuttings are frequently transported from a drilling rig to an off-site facility for disposal. In order to accomplish such off-site disposal, drill cuttings are generally loaded into boxes or other storage containers for transportation away from the rig. While this solution can be generally functional, it is not without significant problems.
One major problem associated with the off-site disposal of drill cuttings is increased cost. In most cases, special equipment is needed to move fluid-laden drill cuttings from a rig's shale shakers to another location on the rig where storage boxes are loaded. Such equipment is often in the form of complicated and elaborate conveyors, augers and/or vacuum units. Moreover, large numbers of storage boxes must be rented or purchased in order to accommodate such cuttings. All of this added equipment and labor increases the costs associated with the drilling process.
Existing methods of cleaning and/or drying drill cuttings in order to remove surface contaminants prior to discharge of such cuttings into the environment have failed to produce satisfactory results. Frequently, existing methods of treating drill cuttings require large amounts of equipment, which can cause space problems on most drilling rigs and add to the overall expense of a drilling project. Further, such existing methods of cleaning and/or drying cuttings frequently utilize surfactants and/or other chemicals which must be disposed of and isolated from the surrounding environment.
Accordingly, the need exists for a method and apparatus for separation of entrained and/or adherent fluids from fluids-laden drill cuttings.
It is an object of the present invention to provide a highly efficient and effective means of separating and removing fluids, and particularly entrained and/or adherent fluids, from drill cuttings.
It is yet another object of the present invention to provide a means of separating and reclaiming fluids from drill cuttings which utilizes a relatively small amount of equipment and, therefore, has minimal space requirements.